‘But say what we can, some one perhaps might be apt to reply, he will still believe his senses, and never suffer any arguments, how plausible soever, to prevail over the certainty of them. Be it so, assert the evidence of sense as high as you please, we are willing to do the same. That what I see and hear, and feel, doth exist, i.e. is perceived by me, I no more doubt than I do of my own being: but I do not see how the testimony of sense can be alleged as a proof for the existence of any thing which is not perceived by sense. We are not for having any man turn sceptic, and disbelieve his senses; on the contrary, we give them all the stress and assurance imaginable, nor are there any principles more opposite to scepticism than those we have laid down, as shall be hereafter clearly shown. Secondly, it will be objected that there is a great difference between real fire, for instance, and the idea of fire, betwixt dreaming or imagining oneself burnt and actually being so: if you suspect it to be only the idea of fire which you see, do but put your hand into it, and you’ll be convinced with a witness. This and the like may be urged in opposition to our tenets. To all which the answer is evident from what hath been already said, and I shall only add in this place, that if real fire be very different from the idea of fire, so also is the real pain that it occasions very different from the idea of the same pain, and yet nobody will pretend that real pain either is, or can possibly be, in an unperceiving thing or without the mind, any more than its idea.’
Now with regard to this system, whatever we may think of the solidity of the foundation, the superstructure is as light and elegant as possible. There is a peculiar character in the metaphysical writings of Berkeley which is to be found no where else. With all the closeness and subtilty of the deepest reflection, they combine the ease and vivacity of a common essay: so that the most violent paradoxes and elaborate distinctions are rendered familiar by the simplicity of the style. His writings show that he had thought with the utmost intensity on almost every subject, yet he has the same careless freedom of manner as if he had never thought at all. He is never entangled in the labyrinth of his own thoughts, and the buoyancy of his spirit surmounts every objection with a singular felicity, as if his mind had wings. It is perhaps worth remarking that the ‘Principles of Human Knowledge’ were published in 1710, at a time when the author was only five-and-twenty, as was the ‘Essay on Vision,’ the greatest by far of all his works, and the most complete example of elaborate analytical reasoning and particular induction joined together that perhaps ever existed. It is also generally free from that air of paradox and fanciful hypothesis which runs through his other writings.[[7]] I mention this the more because I believe that the greatest efforts of intellect have almost always been made while the passions are in their greatest vigour, and before hope loses its hold on the heart, and is the elastic spring which animates all our thoughts.
On the reasoning I have just quoted I will make one or two remarks without pretending to enter into the real difficulties of the question. First, it seems to me that the argument against the existence of the secondary qualities, drawn from the various effects produced by them on different minds or in different circumstances, which Hume mentions as the only solid one, and which Berkeley thinks more doubtful, is no argument at all. That an object at a distance, for example, does not look like the same object near is in consequence of the interposition of the air, which gives it a different hue; the logical inference merely is that one object has not the same sensible qualities as another, or as Berkeley has remarked, since the effect depends upon the combination and reaction of a number of things that we do not know what the true or natural qualities of each object are.
2. The proof of the non-existence of the primary qualities or of matter altogether, as inconceivable by the mind, goes upon the supposition that what is different cannot be the same. ‘An idea,’ says Berkeley, ‘can be like nothing but an idea, a perception like nothing but a perception.’ But it might be proved in this manner that a print cannot resemble a picture, because that which has colour cannot be represented by any thing without colour. That as far as our ideas are perceptions they do not resemble any thing in matter is true, but no one ever supposed that in this respect there was any resemblance between them, or that matter thought. That they cannot be alike in any thing does not seem to me proved by this mode of reasoning: for that our ideas of things are not mere perceptions is evident from this, that they are different among themselves, that is, have other distinguishing qualities besides being perceived.
3. Berkeley’s argument against the existence of matter not merely as the object or archetype, but as the cause of our sensations, is founded on the notion that we have a right to reject every general conclusion in which there is the least flaw or difficulty. Common sense is brought to the bar, like an old offender, and condemned upon the slightest shadow of evidence. If the vulgar system is vulnerable in any part, it is taken for granted that it ought to be discarded, to make room for a perfectly rational and philosophical account, the sufficiency of the understanding being never once doubted. But all this severe logic and scrutiny into the perfect connexion of our ideas vanishes, when the author comes to explain the cause of our external impressions, or to find a substitute for matter. This, he says, is God or an all-powerful spirit, and yet he affirms that we have no more idea of spirit than of matter, and consequently the one ought upon this theory to pass for a nonentity as much as the other.
‘We perceive a continual succession of ideas, some are anew excited, others are changed or totally disappear. There is therefore some cause of those ideas, whereon they depend, and which produces and changes them. That this cause cannot be any quality or idea or combination of ideas, is clear from what has been said. It must therefore be a substance, but it has been shewn that there is no corporeal or material substance. It remains therefore that the cause of ideas is an incorporeal active substance or spirit.
‘A spirit is one simple, undivided, active being: as it perceives ideas, it is called the understanding, and as it produces or otherwise operates about them, it is called the will. Hence there can be no idea formed of a soul or spirit. For all ideas whatever being passive and inert, they cannot represent unto us by way of image or likeness that which acts. Such is the nature of spirit or that which acts, that it cannot be itself perceived, but only by the effects which it produceth. If any man shall doubt of the truth of what is here delivered, let him but reflect and try if he can frame the idea of any power or active being. A little attention will make it plain to any one, that to have an idea which shall be like that active principle of motion and change of ideas, is absolutely impossible.’ That is to say, matter is here excluded from being the cause or in any way the occasion of our ideas, because we know not what it is, and the inference is, that the cause of our ideas must be spirit, of which we are equally ignorant. The reasoning might have been reversed. But it is thus that philosophy seems to be in general nothing else but ‘reason pandering will.’ The literal conclusion from the foregoing argument is, that there is nothing in the universe but oneself, nor even that, but only the present idea: all other words must signify nothing.
To return to Mr. Locke. He has treated on the same question in the second volume, but without advancing any thing remarkable on it, and it is the only place in which he loses his temper, and substitutes ridicule for argument.
In the chapter on Perception, there are some observations on the manner in which our judgments alter the impressions of sensible objects, which are well worth notice, and show that the author was well acquainted with what may be called the practical processes of the human mind.
He says, p. 130, ‘We are farther to consider concerning perception, that the ideas we receive by sensation are often in grown people altered by the judgment without our taking notice of it. When we set before our eyes a round globe of any uniform colour, e.g. gold, alabaster, or jet, it is certain that the idea thereby imprinted in our mind is of a flat circle, variously shadowed with several degrees of light and brightness coming to our eyes. But we having by use been accustomed to perceive what kind of appearance convex bodies are wont to make in us, what alterations are made in the reflections of light by the difference of the sensible figures of bodies, the judgment presently, by an habitual custom, alters the appearances into their causes; so that from that which truly is variety of shadow or colour, collecting the figure, it makes it pass for a mark of figure, and frames to itself the perception of a convex figure and an uniform colour, when the idea we receive from thence is only a plane variously coloured; as is evident in painting. To which purpose I shall here insert a problem of that very ingenious and studious promoter of real knowledge, the learned and worthy Mr. Molineux, which he was pleased to send me in a letter some months since: and it is this: “Suppose a man born blind, and now adult, and taught by his touch to distinguish between a cube and a sphere of the same metal and nigh of the same bigness, so as to tell, when he felt the one and the other, which is the cube, which the sphere. Suppose then the cube and sphere placed on a table, and the blind man made to see: Quere, whether by his sight, before he touched them, he could now distinguish and tell which is the globe, which the cube?” To which the acute and judicious proposer answers, “No. For though he has obtained the experience of how a globe, how a cube affects his touch, yet he has not yet attained the experience that what affects his touch so or so, must affect his sight so or so; or that a protuberant angle in the cube that pressed his hand unequally, shall appear to his eye as it does in the cube.” I agree’ (says Mr. Locke) ‘with this thinking gentleman, whom I am proud to call my friend, in his answer to this his problem; and am of opinion that the blind man at first sight, would not be able with certainty to say, which was the globe, which the cube, whilst he only saw them; though he could unerringly name them by his touch, and certainly distinguish them by the difference of their figures felt. This I have set down, and leave with my reader as an occasion for him to consider how much he may be beholden to experience, improvement, and acquired notions, where he thinks he has not the least use of, or help from them, and the rather, because this observing gentleman farther adds, that having upon the occasion of my book, proposed this to divers very ingenious men, he hardly ever met with one that at first gave the answer to it which he thinks true, till by hearing his reasons they were convinced.’ Mr. Locke then adds other instances to the same effect, as ‘That a man who reads or hears with attention and understanding takes little notice of the characters or sounds, but of the ideas that are excited in him by them. How frequently do we in a day cover our eyes with our eyelids, without at all perceiving that we are in the dark! Men that by custom have got the use of a by-word do almost in every sentence pronounce sounds, which though taken notice of by others, they themselves neither hear nor observe: and therefore it is not so strange that our mind should often change the idea of its sensation into that of its judgment, and make one serve only to excite the other without our taking notice of it.’